I have a rash on my neck. This is the third time it is happening, at the same spot. It starts as a red , slightly bumpy rash, It itches a little. In a day or two it changes color to brown, the skin surface becomes wrinkly and then a kind of scab forms, which starts to peel. In a weeks time the scab peels off, but leaves behind a black scar. I haven t changed any food/lotions/cream/perfume etc. This happened twice in a month. Now the rash has appeared again. I am wondering what is it ?